Study Of Mechanism For The Effect Of Calcium On Drought Resistance In Wheat Seedling

The effects of water deficiency and calcium on the physiological role of wheat seedling (Triticum aevistum Lev Shi 4185) leaves and roots were studied by controlling the osmotic potential under 0.1kg/L, 0.2kg/L, 0.3kg/L PEG-6000 and by regulating Ca2+ level with adding Ca(NO3)2 and EGTA in the cultural solution.The results showed that with the drought stress increasing, the plasma membrane permeability, O2 production rate, MDA content and were raised, SOD activity was obviously increased under light drought stress and decreased under severely drought stress, while POD activity always improved with drought stress being ascended and the relative water content (RWC) of leaves was redueed.The roots activity was highest at slightly drought stress and was decreased with severely drought stress.With the same Ca2+ level, the Ca2+ content and RWC under drought stress by adding 0.2kg/L PEG-6000 were much lower than the normal water providing, while the plasma membrane permeability, O2~ production rate and MDA content and SOD, POD activity were much higher than the normal water providing.Under the normal water-supplying condition, the Ca content, RWC and plasma membrane permeability were not different with Ca2+ being increased and the root activity was changed hardly. O2- production rate, MDA content as well as SOD, POD activity changed gradually.Under drought stress, RWC was increased rapidly and plasma membrane permeability stability declined with the increase of external Ca concentration, the roots activity improved, O2- production rate and MDA content greatly reduced, as Ca content distinctly enhanced. It was obvious that at a certain range of Ca2+-providing treatment stimulated SOD, POD activity and inhibited membrane lipid peroxidation, thus protected it's membrane structure. The effects with EGTA in the cultural solution were contrary.In conclusion, Ca2+ may alleviate the damage of plant under drought stress, which the mechanism is that Ca2+ plays on an important role in increasing roots activity, improving water status, maintaining membrane stability and advancing drought resistance of wheat seedling.